newWriteLocation is the start position in eeprom byteCount is the length of yourString

EEPROM.write(newWriteLocation+byteCount, int(yourString[byteCount]));

Once you start storing data in eeprom, you might need additional routines to:-

search records delete recordsadd new recordsdetermine number of free blocks available

And each of those routines need supporting routines, like you might want to use 2 large arrays, both the same size as eeprom, that you manipulate before writing the entire array back to eeprom, especially if your trying to delete a string and reorder the eeprom to make more efficient use of the available space after the strings been deleted.

It's a real can of worms unless you can find code in the playground that already does what your wanting.